The invention relates to a freight loading system for an aircraft, for loading and/or unloading freight load units, such as containers, pallets or the like, wherein the system includes roller drive units for transporting the freight, latching units for latching the freight, and control units for operating and controlling the roller drive units and/or the latching units.
In conventional freight loading systems, for example as described in German Patent 44 27 696, it is generally known to arrange roller drive units at a certain spacing distance apart from each other within roller tracks in the freight loading space of an aircraft. The roller drive units are coupled in a force-locking manner to the pieces of freight that are to be transported, such as freight containers, pallets or the like, in order to actively transmit a driving force to the respective freight pieces, so as to move them within the freight loading space of the aircraft. The conventional drive rollers of the roller drive units are electrically driven or actuated. These drive rollers suffer a very high wear. Also, due to the very high effective forces, which arise during normal freight transport operations and particularly also if a container is blocked, the drive rollers and the respectively associated electric motors are very often over-loaded and may thus be damaged. As a result, such roller drive units often fail and must be replaced or repaired, which leads to a high maintenance cost and effort.
Further problems arise through the use of electric components such as the above-mentioned electric motors respectively associated with each roller drive unit for driving the rollers, as well as electrical control, supply and switching arrangements. Such electrical components must all be protected against moisture and contamination, and must be electromagnetically shielded, in a complicated and costly manner. Furthermore, electrochemical corrosion arises, which also increases the sensitivity and likelihood of failure of the components.
In view of the high safety requirements onboard an aircraft, the use of such electric components in the freight compartment or cargo hold of an aircraft is necessarily burdened with a high maintenance, handling, inspection or monitoring, and control effort and expense. Nonetheless there always exists a possibility of danger, for example, electrical sparking or the starting of a fire due to a malfunction of an electrical component.
Moreover, since each roller drive unit must be respectively equipped with a driving electric motor, the great number of total roller drive units included in a typical aircraft freight loading system results in a high total weight of such a system, which is undesirable in an aircraft.
Several U.S. Patents disclose various features and embodiments of different conventional freight loading systems, such as U.S. Pat. Nos. 6,139,232; 5,957,640; 5,346,161; 5,316,242; 5,112,173; and 5,090,638; the disclosures of all of which are incorporated herein by reference to provide background information as well as a more complete understanding of the invention.
In view of the above, it is an object of the invention to provide a freight loading system for an aircraft, which makes it possible to load freight into and unload freight from the freight loading space, such as a freight compartment or cargo hold, of an aircraft, in a simple and robust manner. The invention aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification. The invention particularly aims to avoid the dangers and disadvantages associated with using electric components for driving and controlling the roller drive units and the latching units of the freight loading system.
The above objects have been achieved according to the invention in a freight loading system for an aircraft, for loading and/or unloading freight loading units such as containers, pallets or the like, including roller drive units for transporting the freight units, latching units for latching the freight units, and at least one control unit for actuating and controlling the roller drive units and/or the latching units. Particularly according to the invention, at least one of the roller drive units and the latching units is embodied as a pneumatically operating or pneumatically actuated component. Further according to the invention, the system includes at least one pressurized air supply that provides pressurized air through a pressurized air line system to the at least one pneumatic component.
In the inventive system, it is especially advantageous that the dangers associated with sparking or fire generation from electrical devices is entirely avoided or significantly reduced. The use of pneumatic devices for the roller drive units and/or the freight latching units provides a robust, economical system. Overloading of individual components, or the damage, failure or disruption of any one or more of the individual components or pressurized air lines will not lead to a failure of the total pressurized air line system or network. Furthermore, the inventive freight loading system is not sensitive to moisture or contamination, and requires low maintenance. By minimizing or eliminating current-carrying conductors from the freight loading space of the aircraft, an electrochemical corrosion can be avoided, and electromagnetic effects that are incompatible with or interfere with other systems of the aircraft do not arise. By avoiding the use of electric motors for driving the roller drive units, the overall total system weight is reduced.